A vacuum system pipe coupling may be used to couple piping in an exhaust system of a vacuum system. The coupling may comprise a first coupling member having a flange, a second coupling member having flange, an O-ring disposed between the flanges to seal between them and a clamp to releasably clamp the flanges together. The clamp applies an axial force to the flanges to compress the O-ring.
Vacuum pumps are frequently deployed in applications that involve pumping substantial quantities of corrosive fluids, including halogen gases and solvents. Such materials attack the O-rings of pipe couplings, with the result that the O-ring may become excessively plastic or very brittle. This can badly affect the integrity of the seal provided.
The intensity of the attack on the O-ring is dependant on a number of variables including, for example, the pumped fluid, the material from which the O-ring is made and the pump temperature. In exhaust systems, a further variable may be the impact of trace heating used to prevent condensation forming in the exhaust piping.
These problems are particularly acute when pumping reactive gases, such as fluorine, from semi-conductor processing equipment, where gas compositions are varied by reactions in the equipment. Here, even a precise knowledge of the gas flows admitted to the process chamber is a very poor predictor of the quantity or nature of the reactive gas admitted to the pump and hence expelled through the exhaust system.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.